In recent years, improvement in recording density has been remarkable in the field of magnetic recording media used in hard disk drives (HDD). In recent years, the recording density has continuously increased at the astonishing rate of about 1.5 times per year. This improvement in the recording density is supported by a variety of technologies. One of the key technologies is a control technology of slide characteristics between a magnetic head and a magnetic recording medium.
For example, since a CSS (Contact, Start, and Stop) type, called a Winchester type, in which basic operations of contact sliding-floating-contact sliding are performed from start to stop of a magnetic head has become a main technology of hard disk drives, the contact sliding of the magnetic head on a magnetic recording medium cannot be avoided.
For this reason, resolving problems with tribology between a magnetic head and a magnetic recording medium has been the main technical issue up to the present. Thus, efforts to improve a protective film laminated on a magnetic film of a magnetic recording medium have continued, and abrasion resistance and slide resistance on the surface of the magnetic recording medium are the main areas of improvement in reliability of the magnetic recording medium.
Protective layers made of various materials in magnetic recording media have been suggested. However, carbon films have mainly been utilized from the overall viewpoint of film formation properties, durability, and the like. Further, the hardness, density, coefficient of kinetic friction, and the like of the carbon films are significantly reflected on the CSS characteristics or corrosion resistance of magnetic recording media. Therefore, the hardness, density, coefficient of kinetic friction, and the like of the carbon films are very important.
However, the durability of the magnetic recording media is not sufficiently ensured merely by forming the protective film. Therefore, a lubricant membrane is formed on the surface of the protective film. The main roles of the lubricant membrane are to prevent a protective film or the like of a magnetic recording medium from being in direct contact with the atmosphere in order to improve corrosion resistance, to prevent a magnetic head slider from coming into direct contact with the protective film when the magnetic head slider accidentally comes into contact with a data surface of the magnetic recording medium, and to considerably reduce the frictional force of the magnetic head slider that slides on the magnetic recording medium.
Here, the thickness of a lubricant membrane formed on the surface of a magnetic recording medium is precisely managed within a unit of sub-nm. Therefore, as a method of forming a lubricant membrane, a so-called dipping method of immersing a magnetic recording medium into an immersion tank that has a liquid lubricant and then raising the magnetic recording medium from the immersion tank so that a lubricant membrane with a uniform thickness is formed on the surface of the magnetic recording medium has been widely used in the past (for example, see Patent Literature 1). In this dipping method, batch processing is generally used in terms of mass production. Therefore, collective processing is performed by immersing a plurality of magnetic recording media arranged in parallel into an immersion tank.
[Patent Document 1] Patent Application Laid-Open Publication No. 6-150307